1. Technical Field
This application relates to file systems and more particularly to techniques used in connection with distributed file systems and providing a consistent snapshot thereof.
2. Description of Related Art
Computer systems may include different resources used by one or more host processors. Resources and host processors in a computer system may be interconnected by one or more communication connections. These resources may include, for example, data storage devices such as those included in the data storage systems manufactured by EMC Corporation. These data storage systems may be coupled to one or more servers or host processors and provide storage services to each host processor. Multiple data storage systems from one or more different vendors may be connected and may provide common data storage for one or more host processors in a computer system.
A host processor may perform a variety of data processing tasks and operations using the data storage system. For example, a host processor may perform basic system I/O operations in connection with data requests, such as data read and write operations.
Host processor systems may store and retrieve data using a storage device containing a plurality of host interface units, disk drives, and disk interface units. The host systems access the storage device through a plurality of channels provided therewith. Host systems provide data and access control information through the channels to the storage device and the storage device provides data to the host systems also through the channels. The host systems do not address the disk drives of the storage device directly, but rather, access what appears to the host systems as a plurality of logical disk units. The logical disk units may or may not correspond to the actual disk drives. Allowing multiple host systems to access the single storage device unit allows the host systems to share data in the device. In order to facilitate sharing of the data on the device, additional software on the data storage systems may also be used.
Host systems may receive requests from clients in accordance with a variety of different protocols and different versions thereof including, for example, file access protocols, and block service requests. With a file access protocol, clients issue requests to access a file system. Such clients do not have direct access to the underlying block storage but rather interact with one or more hosts acting as file servers providing file system services based on a particular file access protocol. A variety of different data services may be used in connection with a data storage system. Such data services may include data replication and backup facilities that may vary with the underlying data storage system.
In some systems, clients accessing data in a file system may communicate through a single communication or access point on a server. The server and underlying data storage system where the file system is stored have limited resources for use in connection with servicing client requests. Thus, it may be desirable to use efficient techniques such as in connection with the file system, servicing client requests and providing various data services in order to better utilize resources and respond to client requests in a timely manner.